as in treacherous
formal
causing harm in a way that is gradual or not easily noticed
Most people with this insidious disease have no idea that they are infected. an insidious enemy
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Example Sentences
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Recent Examples of insidious
Complicating matters is the insidious Host character (voiced by Len Cunningham’s father, Liam Cunningham), who manipulates the players’ reality.
—
Jennifer Maas, Variety, 2 Oct. 2025
But the long-term story is more insidious.
—Bill Frist, Forbes.com, 18 Sep. 2025
And that’s especially true when a demon as insidious as Doma or brutal as Akaza steps into frame (special shout-out to the deliciously cruel and twisted sympathy Doma shares for his opponent Shinobu Kocho during their fight).
—David Opie, IndieWire, 10 Sep. 2025
This in our view is the insidious threat social media and rapidly growing AI capabilities pose to society and culture.
—The Editorial Board, Chicago Tribune, 31 Aug. 2025
See All Example Sentences for insidious
Jennifer Maas, Variety, 2 Oct. 2025
But the long-term story is more insidious.
—Bill Frist, Forbes.com, 18 Sep. 2025
And that’s especially true when a demon as insidious as Doma or brutal as Akaza steps into frame (special shout-out to the deliciously cruel and twisted sympathy Doma shares for his opponent Shinobu Kocho during their fight).
—David Opie, IndieWire, 10 Sep. 2025
This in our view is the insidious threat social media and rapidly growing AI capabilities pose to society and culture.
—The Editorial Board, Chicago Tribune, 31 Aug. 2025
See All Example Sentences for insidious
Recent Examples of Synonyms for insidious
Adjective
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An experienced hiker from San Diego attempting to climb the tallest peak in the contiguous United States has fallen to his death amid treacherous winter conditions, leaving his two young sons and family in shock and grief.—
Amanda Lee Myers,
USA Today,
31 Oct. 2025
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Subtitled Into the Grand Line, the next arc will see the Straw Hats enter the treacherous expanse of water called the Grand Line and visit various locations in and around this territory.—
Nick Romano,
Entertainment Weekly,
28 Oct. 2025
Adjective
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Featuring a subtle kick flare at the hem and chic pintuck detailing, they’re designed to hit right under the calf, or just at the ankle for petite people like myself.—
Sophie Dodd,
Travel + Leisure,
26 Oct. 2025
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Adding parsnips and turnips to the recipe gives the dish a subtle earthy flavor that perfectly complements the savory chicken.—
Sarah Martens,
Better Homes & Gardens,
25 Oct. 2025
Adjective
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Several residents who work in the Georgia King Village area weighed in on the incident, including Harriette Guity, who told News12 that false reports based on AI could stretch first responders thin.—
Kimberlee Speakman,
PEOPLE,
25 Oct. 2025
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Archaeologists concluded the structure was actually a false tomb, or a cenotaph, a type of burial monument erected to honor a deceased person buried elsewhere.—
Aspen Pflughoeft,
Miami Herald,
24 Oct. 2025
Adjective
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The lawsuit, filed in New York federal court on Tuesday, brings claims for deceptive practices and false advertising, among others.—
Winston Cho,
HollywoodReporter,
5 Nov. 2025
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The complaints allow the public to report unfair or deceptive business practices, according to the agency’s website, and can prompt investigations from the office.—
Nicole Blanchard,
Idaho Statesman,
3 Nov. 2025
Adjective
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Her Ashley is the movie’s fourth and fifth wheel, dismissed as both a perfidious troublemaker and a New Age airhead—a life coach in need of a wife coach.—
Justin Chang,
New Yorker,
22 Aug. 2025
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This perfidious situation, unintentional as its creation may have been, was strongly critiqued as far back as 1983 by Jonathan Crush and Paul Wellings in an article in The Journal of Modern African Studies.—
The Editors,
JSTOR Daily,
15 Aug. 2025
Adjective
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The Wild earned a power play for the incorrect challenge but couldn’t extend the lead to 2-0.—
Michael Russo,
New York Times,
31 Oct. 2025
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Trump has also mistakenly claimed that China and Russia are currently testing nuclear weapons and directed the incorrect agency — the Department of War — to resume testing rather than the Department of Energy, which oversees the nation’s nuclear warheads, Sanders-Zakre said.—
Joshua Rhett Miller,
MSNBC Newsweek,
30 Oct. 2025
Adjective
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While most plot details remain under wraps, The Hollywood Reporter previously revealed that one plot point centers on the son of Stiller and Polo’s characters, who gets engaged to a ball-busting woman who seems all wrong for him.—
Carly Thomas,
HollywoodReporter,
2 Nov. 2025
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The right kiss will save them, but the wrong one will kill them.—
Brittany Johnson,
PEOPLE,
2 Nov. 2025
Cite this Entry
“Insidious.” Merriam-Webster.com Thesaurus, Merriam-Webster, https://www.merriam-webster.com/thesaurus/insidious. Accessed 7 Nov. 2025.
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